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Create contingency tables
What is a contingency table A contingency table, also called cross-tab, is an efficient way to summarize the relation (or correspondence) between two categorical variables V1 and V2. It has the following structure: V1 V2 Category 1 Category j … Category m2 Category 1 n(1,1) n(1,j) … n(1,m2) … … … … … Category i n(i,1) n(i,j) … n(i,m2) … … … … … Category m1 n(m1,1) n(m1,j) … n(m1,m2) where n(i,j) is...
Monte Carlo simulations
What is a Monte Carlo Simulation in XLSTAT? Monte Carlo Simulation is a module that allows building and computing simulation models, an innovative method for estimating variables, whose exact value is not known, but that can be estimated by means of repeated simulation of random variables that follow certain theoretical laws. Before running the model, you need to create the model, defining a series...
ANCOVA (Analysis of Covariance)
What is ANCOVA (Analysis of Covariance) ANCOVA (ANalysis of COVAriance) can be seen as a mix of ANOVA and linear regression as the dependent variable is of the same type, the model is linear and the hypotheses are identical. In reality it is more correct to consider ANOVA and linear regression as special cases of ANCOVA. The ANCOVA model If p is the number of quantitative variables, and q the number...
Parallel coordinates plots
What is Parallel Coordinates Visualization This visualization method is useful for data analysis when you need to describe groups using variables. For example, this method could be used on groups generated by Agglomerative Hierarchical Clustering. Using this method you are able to visually determine which variables are discriminative. Structure of a Parallel Coordinates plot If you consider N observations...
Missing data
Which are the types of missing values? There are three types of missing values (Allison, 2001): data missing completely at random (MCAR), data missing at random (MAR) and data not missing at random (NMAR). Data is missing completely at random (MCAR) if the event that leads to a missing data is independent of observable variables and of unobservable parameters. It should occur entirely at random. When...
Statistical Power for proportion comparison
Statistical Power analysis for the comparison of proportions in XLSTAT XLSTAT includes parametric tests and nonparametric tests to compare proportions. Thus we can use the z-test (for one or two proportions), chi-square test, the sign test or the McNemar test. XLSTAT can calculate the power or the number of observations necessary for these tests using either exact methods or approximations. When testing...
Univariate plots
Before using advanced analysis methods you must first of all reveal the data in order to identify trends, locate anomalies or simply have available essential information such as the minimum, maximum or mean of a data sample. XLSTAT offers you a large number of descriptive statistics and charts which give you a useful and relevant preview of your data. Although you can select several variables (or...
Statistical Power for logistic regression
Statistical Power for Logistic regression XLSTAT-Base offers a tool to apply logistic regression. XLSTAT-Power estimates the power or calculates the necessary number of observations associated with this model. When testing a hypothesis using a statistical test, there are several decisions to take: The null hypothesis H0 and the alternative hypothesis Ha. The statistical test to use. The type I error...
Preference Mapping (PREFMAP)
What is preference mapping? Preference Mapping allows to build maps which are useful in a variety of domains. A preference map is a decision support tool in analyses where a configuration of objects has been obtained from a first analysis (PCA, MCA, MDS), and where a table with complementary data describing the objects is available (attributes or preference data). There are two types of preference...
CONTOUR PLOT AND SURFACE PLOT
WHAT ARE CONTOUR PLOT AND SURFACE PLOT? Contour plot and surface plot represent a three-dimensional surface by drawing contours on a two-dimensional plane. The X and Y values are plotted along the respective axes, while the contour lines and bands depict the Z value. The difference between the two types of plots is the infill between the contour lines – this is only present in the surface plot. This...